Calibrated, low-profile magnetic sensor

• US 20040032251A1
• Filed: 08/14/2002
• Published: 02/19/2004
• Est. Priority Date: 08/14/2002
• Status: Active Grant

• Current Assignee: Sensata Technologies Incorporated (Sensata Technologies Holding Plc)
• Original Assignee: Honeywell International Inc.
• Inventors: Mueller, Douglas L., Zimmerman, Mike W., Stolfus, Joel D., Ricks, Lamar F., Johnson, Curtis B.
• Granted Patent: US 6,798,193 B2
• Time in Patent Office: Days
• US Class Current: 324/207.13
• CPC Class Codes: G01D 5/147 influenced by the movement of a third element, the position of Hall device and the source of magnetic field being fixed in respect to each other
• CPC Class Codes: G01R 33/06 using galvano-magnetic devices
• CPC Class Codes: Y10T 29/49007 Indicating transducer

Abstract

A calibrated, low-profile magnetic sensor and method for forming such a sensor are described herein. Generally, a magnetic sensing device is formed within a housing, wherein the magnetic sensing device comprises at least one magnet. The magnetic sensor includes a compact integrated circuit package such as, for example, a small outline integrated circuit package (SOIC). A magnetic sensing element is generally mounted to the compact integrated circuit package. The magnetic sensing device can be configured to additionally incorporate a printed circuit board (PCB) having a hole formed therein such that the compact integrated circuit package can be surface mounted off-center on the printed circuit board, so that the hole can be located within the printed circuit board to match a shape of the magnet, allowing the magnet to pass through the circuit board adjacent to the SOIC to complete the magnetic circuit. An orifice placed with in the housing permits a tool to be passed through the orifice within the housing to contact the magnet. The magnet can be placed in the optimum position for calibration of the magnetic circuit thereof. The same orifice that is used for calibrating the position of the magnet can also be utilized as an injection port for encapsulating the device using an injection epoxy dispensing process.

Claims

1. A calibrated, low-profile magnetic sensor, wherein said magnetic sensor comprises:

a magnetic sensing device formed within a housing, wherein said magnetic sensing device comprises at least one magnet;

a compact integrated circuit package, wherein a magnetic sensing element is mounted to said compact integrated circuit package; and

a printed circuit board having a hole formed therein, wherein said compact integrated circuit package is surface mounted off-center on said printed circuit board so that said hole is located within said printed circuit board to receive said at least one magnet, thereby permitting said magnet to pass through said hole to complete a magnetic circuit thereof.

2. The magnetic sensor of claim 1 wherein said housing comprises an orifice wherein a tool is permitted to pass through said orifice within said housing to contact said at least one magnet to position said at least one magnet to a calibrated position thereof.

3. The magnetic sensor of claim 2 wherein said orifice is adapted for use with an epoxy injection dispensing process to encapsulate and seal said magnetic sensing device.

4. The magnetic sensor of claim 1 wherein said at least one magnet passes through said hole within said printed circuit board and adjacent to said compact integrated circuit package to complete a magnetic circuit thereof.

5. The magnetic sensor of claim 1 wherein said at least one magnet is mounted through said printed circuit board within said housing to provide a magnetic circuit thereof.

6. The magnetic sensor of claim 1 further comprising a plurality of ribs to provide a press fit for maintaining said at least one magnet in a calibrated position within said magnetic sensor.

7. The magnetic sensor of claim 1 wherein at least one groove is formed in said housing to receive a seal thereof.

8. The magnetic sensor of claim 7 wherein said seal comprises an O-ring seal positioned within said at least one groove.

9. The magnetic sensor of claim 1 wherein said compact integrated circuit package comprises a small outline integrated circuit package (SOIC).

10. The magnetic sensor of claim 1 wherein said at least one magnet comprises a small outline magnet.

11. The magnetic sensor of claim 2 wherein said orifice comprises an epoxy injection port used for an epoxy injection dispensing process and for tool access for a magnet position calibration.

12. The magnetic sensor of claim 2 wherein said at least one magnet is located coincident with an axis of said orifice.

13. The magnetic sensor of claim 1 further comprising a plastic cover that surrounds and protects said printed circuit board, said at least one magnet and said compact integrated circuit package.

14. The magnetic sensor of claim 1 wherein said orifice comprises:

a port for epoxy injection dispensing; and

a hole for tool access for magnet position calibration.

15. The magnetic sensor of claim 1 further comprising a plurality of lead terminals.

16. The magnetic sensor of claim 1 wherein said tool comprises a calibration tool.

17. A calibrated, low-profile magnetic sensor, said magnetic sensor comprising:

a magnetic sensing device formed within a housing, wherein said magnetic sensing device comprises at least one magnet;

a compact integrated circuit package, wherein a magnetic sensing element is mounted to said compact integrated circuit package; and

a printed circuit board having a hole formed therein, wherein said compact integrated circuit package is surface mounted off-center on said printed circuit board so that said hole is located within said printed circuit board to receive said at least one magnet, thereby permitting said magnet to pass through said hole to complete a magnetic circuit;

wherein said housing comprises an orifice wherein a tool is permitted to pass through said orifice within said housing to contact said at least one magnet to position said at least one magnet to a calibrated position thereof and wherein said orifice is adapted for use with an epoxy to encapsulate and seal said magnetic sensing device.

18. A method for forming a magnetic sensor, said method comprising the steps of:

forming a magnetic sensing device within a housing, wherein said magnetic sensing device comprises at least one magnet;

mounting a magnetic sensing element to a compact integrated circuit package; and

forming a hole within a printed circuit board, wherein said compact integrated circuit package is surface mounted off-center on said printed circuit board so that said hole is located within said printed circuit board to receive said at least one magnet, thereby permitting said magnet to pass through said hole to complete a magnetic circuit thereof.

19. The method of claim 18 further comprising the step of:

configuring said housing to comprise an orifice wherein a tool is permitted to pass through said orifice within said housing to contact said at least one magnet to position said at least one magnet to a calibrated position.

20. The method of claim 19 further comprising the step of:

adapting said orifice for use with an injection dispensing epoxy to encapsulate and seal said magnetic sensing device.

21. The method of claim 18 further comprising the step of:

passing said at least one magnet through said hole within said printed circuit board and adjacent to said compact integrated circuit package to complete the magnetic circuit.

22. The method of claim 18 further comprising the step of:

mounting said at least one magnet through said printed circuit board within said housing to provide the magnetic circuit thereof.

23. The method of claim 18 further comprising the step of:

configuring said magnetic sensor to comprise a plurality of ribs to provide a press fit for maintaining said at least one magnet in a calibrated position within said magnetic sensor.

24. The method of claim 18 further comprising the step of:

forming at least one groove in said housing to receive a seal.

25. The method of claim 24 wherein said seal comprises an O-ring seal positioned within said at least one groove.

26. The method of claim 18 wherein said compact integrated circuit package comprises a small outline integrated circuit package (SOIC).

27. The method of claim 18 wherein said at least one magnet comprises a small outline magnet.

28. The method of claim 19 further comprising the step of:

configuring said orifice to comprise an epoxy injection port used for an epoxy injection dispensing process and for tool access for a magnet position calibration.

29. The method of claim 19 further comprising the step of:

locating at least one magnet coincident with an axis of said orifice.

30. The method of claim 18 further comprising the step of:

forming a plastic cover that surrounds and protects said printed circuit board, said at least one magnet, and said compact integrated circuit package.

31. The method of claim 18 further comprising the step of configuring said orifice to comprise:

a port for epoxy injection dispensing; and

a hole for tool access for magnet position calibration.

32. The method of claim 18 further comprising the step of:

configuring said magnetic sensor to comprise a plurality of lead terminals.

33. The method of claim 18 wherein said tool comprises a calibration tool.

34. A method for forming a calibrated, low-profile magnetic sensor, said method comprising the steps of:

forming a magnetic sensing device within a housing, wherein said magnetic sensing device comprises at least one magnet;

mounting said magnetic sensing device to a compact integrated circuit package; and

forming a hole within a printed circuit board, wherein said compact integrated circuit package is surface mounted off-center on said printed circuit board so that said hole is located within said printed circuit board to match a shape of said at least one magnet, thereby permitting said magnet to pass through said hole to complete a magnetic circuit;

configuring said housing to comprise an orifice wherein a tool is permitted to pass through said orifice within said housing to contact said at least one magnet to position said at least one magnet to a calibrated position thereof; and

adapting said orifice for use with an epoxy injection dispensing process to encapsulate and seal said magnetic sensing device.